The pope, who has spoken out against drug use before, said: “To think that harm can be reduced by permitting drug addicts to use narcotics in no way resolves the problem. Attempts, however limited, to legalise so-called recreational drugs, are not only highly questionable from a legislative standpoint, but they fail to produce the desired effects.”

On Saturday Francis is due to visit Calabria, home of Italy’s powerful ‘Ndrangheta mafia, which controls a significant share of the global trade in illegal narcotics. The pope said drug use was “fed by a deplorable commerce which transcends national and continental borders” and was placing increasing numbers of young people at risk of harm.

Addressing heads of world anti-drug agencies at the 31st International Drug Enforcement Conference, the pope said: “I would reaffirm what I have stated on another occasion – no to every type of drug use. It is as simple as that … But to say this no, one has to say yes to life, yes to love, yes to others, yes to education, yes to greater job opportunities. If we say yes to all these things, there will be no room for illicit drugs, for alcohol abuse, for other forms of addiction.”